Xerostomia (dry mouth syndrome) is the result of compromised salivary flow and is associated with a wide variety of conditions and causative agents. The condition can be the result of a pathological state such as Sicca Syndrome (Sjogren's disease), dry gland disease, polyglandular failure disfunction, and the like. According to a 1986 National Institute of Dental Research publication, over 300 commonly used drugs listed dry mouth as a side effect of their use, the most prevalent of which were the hypertensives and anti-depressants, while others included pain killers, tranquilizers, diuretics and even over-the-counter antihistamines. In addition, treatments such as radiation treatment for tumors in the head and neck region can cause the sensation of dry mouth. Furthermore, age and stress have been linked to xerostomia.
The compromised salivary flow is frequently responsible for a variety of symptoms such as a burning sensation in the mouth, difficulty with speech, eating and tasting, and the like. It can lead to mucosal infections, bacterial sialadentis, periodontal disease and dental caries.
Dry mouth sufferers have used a variety of self-help treatments, but these have not been particularly satisfactory. Liquid remedies such as water and artificial saliva offer short lived help, and the artificial saliva exhibits a consistency similar to natural saliva which some sufferers view as distasteful. Solid aids such as citric rinds and hard candies are damaging to tooth enamel and extend no lubricating comfort.
A Jaboradini derivative, pilocarpine, has been used as a sialogogue drug with success. However, the drug is a muscarinic agonist which is known to produce such non-specific systemic side effects as excessive tearing and runny noses. The drug also presents the danger of cardiac arrest if misused.
Numerous are the approaches which have been taken to soothe dry mouth discomfort appear in the literature. Some, like those described in U.S. Pat. No. 4,088,788 use masticatory stimulation to induce salivation and some like in U.S. Pat. No. 4,400,372 use an acid containing chewing gum to achieve both masticatory and gustatory stimulation. U.S. Pat. No. 5,156,845 teaches a lozenge with an acidulate, employing gustatory stimulation to relieve oral dryness and also includes a fluoride source to promote remineralization of the teeth. U.S. Pat. No. 4,265,877 describes a chewing gum which includes a fluoride source for the same purpose.
Hutchinson describes the development of artificial saliva tablets in New Zealand Pharmacy, 7:30, 1987. He had been using an artificial saliva but characterized it as a "better-than-nothing" approach. The reason was that it supported mold growth after a short time, the relief achieved was temporary unless the fluid was continuously applied, which meant considerable social inconvenience, and the sorbitol used in the product caused irritation and painful sensations of the tongue and mucosa. Noting that polyethylene oxide as a 2% solution had been used with advantage, Hutchinson proceeded to prepare tablets which when slowly sucked, taking sips of water, dissolved in the mouth, coating the mucosa and relieving systems of xerostomia. Formulations containing polyethylene oxide alone or 70-90% polyethylene oxide combined with citric acid (with or without flavoring and sweetener) were prepared. After "some disastrous results" the citric acid was eliminated as it appeared to be inhibiting the tableting flow properties, possibly due to uptake of water from the atmosphere.
While Hutchinson apparently noted no advantage to the citric acid and abandoned its use due to formulation difficulties, it has now been discovered that a highly advantageous product for the relief of the symptoms of xerostomia can be achieved by employing both polyethylene oxide and citric acid, if appropriately formulated.
It is accordingly the object of the invention to provide a novel composition which is advantageous for relief of the symptoms of xerostomia. This and other objects of the advantage will become apparent to those of ordinary skill in the art of formulation from the following detailed description.